1. Field of the Invention
This invention relates to a locking device for two components which are in a mutual screw connection.
This invention also relates to a pipe coupling provided with such a device.
The function of the locking device is to prevent undesirable unscrewing of the two components from each other, in particular in applications where the two components are subject to vibrations or shaking during use.
The invention is more particularly but not limitatively aimed at standardized couplings comprising a nipple at the end of one of the pipes, intended to be pressed into a flaring of the end of the other pipe, by tightening a nut captively mounted on one of the pipes and engaging a thread formed on the other pipe.
2. Description of Related Art
U.S. Pat. No. 6,293,595 B1 describes such a locking device capable of simultaneously engaging, by an axial movement under pressure from a spring, the hexagonal formation of the nut and a stop component integral with the male end-portion of the pipe. In order to be able to separate the two pipe end-portions, the coupling component must be pushed back against the return spring to the position where it is disconnected from the hexagonal formation provided on the nut and/or from the stop component attached to the male end-portion of the pipe.
During screwing or unscrewing, the presence of the tool on the nut prevents the coupling component from returning to the locking position. As soon as the tool is withdrawn when the screwing operation is completed, the coupling component is free to move to the locking position through the action of the spring.
This known device has the considerable advantage of being able to be adapted to a standard pipe coupling without modifications other than merely securing a bearing element on the male end-portion of the coupling.
In certain applications, where accessibility is difficult, in particular in aeronautics, it is desirable to minimize the interference caused by the locking device. With the known device, if the nut resists the unscrewing force exerted by the operator, the operator, who cannot see the nut, does not know whether the resistance is due to the screwing connection itself or to an incorrect disengagement of the coupling component. Moreover, and in any case, he must remember the structure of the locking device in order to displace his tool axially along the hexagonal formation thereby to push the coupling component back before being able to perform the unscrewing operation strictly speaking.